Automatic dbjll-pipe ctjtteb



July-10, 192s. l www@ vK. F. MITCHELL AUTOMATIC DRILL PIPE CUTTER Filed Aug. 15, 19.27

Patented July lll, i928,

KEARNEY FELIX MITCHELL, OF SULPI-IUR, LOUISIANA.

AUTOMATIC DRILL-PTFE CUTTER.

Application filed August 15, 1927,

This invention relates to pipe cutters tor use in cutting the drill pipe in an oil well when the pipe becomes stuclr in the hole.

The object of the invention is to provide an automatic drill pipe cutter, including` a sleeve adapted to encircle the. drill pipe and to be lowered into the well, the said sleeve carrying the cutting bits, and means for bringing the bits automatically into engagement with the work.

ln the drawing` Figure 1 is a longitudinal sectional view oi the pipe cutting` tool as operatively7 mounted upon a drill pipe, the cutting bits being disengaged from the pipe;

Figure 2 is a view similar to Figure 1, with the exception that the cutting bits are here shown in engagement with the pipe 'for cutting the same;

Figure 8 is a cross section on the line 3 3 ot Figure 1.

The invention comprises a hollow, cylindrical shell 1, having an ordinary screw coupling 2 for connecting to a suitable length ot' operating pipe 15 for lowering the device into the well (not shown). The upper end of the shell 1 is interiorly threaded as shown at 8, and a bit compressing collar 4 is formed to lit within the shell 1, and is threaded upon its outer periphery to loosely mesh with the inner threads 3 of the shell 1. Permanently mounted upon the upper end of the collar 4 is a coiled spring 5, the tree or upper end ot the said spring being formed into a ring G from which eX- tend the flexible and inwardly directed lock prongs 7, the said prongs being directed axially upward. The lower end of the collar 4 has its interior wall beveled ott conically, as shown at 8, the said wall feathering out towards the wall ot the shell 1 at the lower portion of the collar4. A pair of cutter bars 9 are pivoted at diametrically opposite points 10 upon the interior wall of the shell 1, substantially below the collar 4, the upper ends of the bars 9 being extended within the lower conical end ot the collar 4 and being formed into inwardly directed bits 9. The cutter bars 9 are normally forced asunder against the wall of the shell l by flat springs 11.

Serial N0, 212,935.

Tn use the device is lowered over the drill pipe 12, the prongs 7 expanding as they pass over the joint 13 to the drill pipe. AThe device is then partially retracted, whereupon the upper or 'free ends ot the prongs 7 en gage the joint 13, thus compressing the Spring 5 and thereby anchoringl the collar 4 against rotation when the shell 1 is rotated. The shell 1 being now rotated, the collar 4 1s caused to travel down the shell by virture ot the intermeshing threads 3 and 4, thus causing the lower tapered wall of the collar 4 to torce the cutter bars 9 axially inwardly, and causing the bits 9 to bite into the pipe 12. Thus, the cutter bars 9 and bits 9 rotating with the shell 1, while the pipe 12 remains stationary, the resulting action is the cutting or severing ot the pipe 12.

lVhile l have herein described a certain speci tic manner and method of constructing and assembling the elements of my invention, it is understood that I may vary from the saine in minor details, not departing from the spirit of my invention, so as best to construct a practical device for the purpose intended, as defined in the appended claim.

l claim:

A. drill pipe cutter, comprising a cylindrical shell adapted for vertical disposition within the well and over the drill pipe, the upper end ot the shell beinginteriorly threaded; means for connecting the shell with an operating pipe; a bit compressing collar threadly engaging the threaded upper end ot the said shell, the lower end of the collar having its inner wall beveled oil:l conically; a coil spring mounted upon the upper end of the said collar; lock prongs mounted upon the upper end of the said spring; cutter bars pivoted oppositely upon the interior wall of the shell below the said bit compressing collar and having their upper ends entending upwardly within the said conical lower end of the said bit compressing collar; inwardly directed bits at the upper` ends of the said cutter bars; and means for normally forcing` the cutter bars asunder.

Tn testimony whereof T alix my signature.

KEARNEY FELIX MITCHELL. 

